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      <title>ES如何处理数据的分布和均衡？如何在集群中重新分配分片？ - 交互式测验</title>
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          <div class="quiz-container">
            <div class="quiz-header">
              <h1>ES如何处理数据的分布和均衡？如何在集群中重新分配分片？ - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
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            <div id="quiz-content">
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      <script>
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  {
    "question": "在Elasticsearch中，副本分片（Replica Shard）最主要的作用是什么？",
    "options": [
      "协调集群中所有分片的重新分配过程。",
      "通过哈希计算决定新文档应写入哪个分片。",
      "提高数据的可用性和容错能力，在主分片故障时提供服务。",
      "接收和存储原始文档数据。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "副本分片是主分片的精确复制。其核心价值在于提供数据冗余，当持有主分片的节点发生故障时，副本分片可以被提升为新的主分片，从而保证数据的可用性和服务的连续性，实现容错。",
    "source": "文档中「1. 数据的分布和均衡」部分",
    "hint": "思考一下，如果某个持有主分片的节点突然宕机了，集群该如何保证数据不丢失且服务能继续？"
  },
  {
    "question": "当一个新文档被写入Elasticsearch索引时，系统是如何决定它应该存储在哪个主分片（Primary Shard）上的？",
    "options": [
      "写入到当前磁盘空间最空闲的主分片上。",
      "通过对文档的 `_id` 进行哈希计算来确定。",
      "同时写入到所有主分片，以确保数据完整性。",
      "由主节点（Master Node）根据当前集群负载情况实时指派。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "Elasticsearch通过一个路由算法来确定文档的存储位置。该算法会对文档的 `_id`（或者指定的路由键）进行哈希运算，然后根据哈希值和索引的主分片数量计算出目标主分片。这种方式保证了数据写入的确定性和高效性。",
    "source": "文档中「1. 数据的分布和均衡」->「数据分布的关键点」部分",
    "hint": "文档中提到了一个关键的文档元数据字段 `_id` 和一个数学运算。"
  },
  {
    "question": "根据文档描述，Elasticsearch为了避免单点故障，其分片分配策略遵循的一个关键原则是什么？",
    "options": [
      "优先将主分片分配在集群的主节点（Master Node）上以提高写入性能。",
      "确保主分片和其所有副本分片都分布在不同的节点上。",
      "总是将所有副本分片集中存放在一个专用的备份节点上。",
      "保证每个节点上的主分片数量和副本分片数量完全相等。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "为了实现高可用，Elasticsearch的智能分配策略会确保一个主分片和它的副本分片不会被分配到同一个物理节点上。这样，即使某个节点完全失效，该节点上的主分片数据在其他节点上依然有副本存在，不会导致数据丢失。",
    "source": "文档中「1. 数据的分布和均衡」->「数据分布的关键点」部分",
    "hint": "为了防止一个节点坏掉导致某个分片的主副本和所有副本都失效，系统应该怎么做？"
  },
  {
    "question": "在分片重新分配（Rebalancing）的过程中，主节点（Master Node）扮演了什么核心角色？",
    "options": [
      "负责将分片数据从源节点物理复制到目标节点。",
      "临时存储正在迁移的分片数据，作为中转站。",
      "仅负责检测节点故障，具体的分配决策由各数据节点自行协商。",
      "负责协调整个过程，包括做出分配决策和更新最终的集群状态。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "主节点是集群的“大脑”，在分片重新分配中，它负责监控集群状态，当检测到触发条件后，它会根据分配策略计算出最优的分配方案，然后向相关数据节点发出指令，并在迁移完成后更新整个集群的状态信息。数据传输本身是在数据节点之间直接进行的。",
    "source": "文档中「2. 分片的重新分配（Rebalancing）」->「分片重新分配的机制」部分",
    "hint": "文档中明确指出“Elasticsearch 的分片重新分配由主节点（Master Node）负责协调...”。"
  },
  {
    "question": "以下哪种情况通常不会触发Elasticsearch的分片重新分配（Rebalancing）过程？",
    "options": [
      "更新索引中某个文档的内容。",
      "集群中新增了一个数据节点。",
      "管理员通过API手动执行了reroute命令。",
      "集群中有一个节点因故障宕机。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "分片重新分配是集群拓扑结构或状态发生变化时的一种宏观调整行为，例如节点的加入、离开或故障。而更新单个文档内容是一个数据层面的操作，它只会在文档所属的那个主分片及其副本分片内部进行，不会引起分片在节点间的移动。",
    "source": "文档中「2. 分片的重新分配（Rebalancing）」部分",
    "hint": "思考一下，哪个选项是文档级别的操作，而其他选项是集群节点级别的事件？"
  },
  {
    "question": "Elasticsearch中的“磁盘水位策略（Disk Watermarking）”其主要目的是什么？",
    "options": [
      "记录每个分片占用的磁盘空间，用于生成存储报告。",
      "当节点磁盘使用率达到阈值时，自动将分片移走以避免磁盘被写满。",
      "在磁盘空间不足时，自动删除最旧的数据。",
      "限制单个索引可以占用的最大磁盘空间。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "磁盘水位策略是一种主动的保护机制。通过设置低水位和高水位阈值，当某个节点的磁盘使用率超过高水位线时，Elasticsearch会停止向该节点分配新的分片，并尝试将该节点上现有的分片迁移到其他磁盘空间更充裕的节点上，从而防止节点因磁盘耗尽而崩溃。",
    "source": "文档中「4. 管理和配置分片重新分配」部分",
    "hint": "这个策略的名称“水位”暗示了它与资源使用达到某个水平线有关。"
  },
  {
    "question": "根据文档，哪个因素直接影响分片重新分配过程中数据迁移的速度和效率？",
    "options": [
      "主节点（Master Node）的CPU负载。",
      "集群的健康状态（黄色或红色）。",
      "节点之间的网络带宽。",
      "索引中包含的文档总数。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "分片迁移的本质是在两个数据节点之间进行大量的数据复制。因此，这两个节点之间的网络带宽和稳定性是数据传输速度的瓶颈，直接决定了重新分配过程需要花费多长时间。虽然其他因素也相关，但网络带宽是影响数据传输速率的核心物理限制。",
    "source": "文档中「3. 影响分片重新分配的因素」部分",
    "hint": "分片重新分配过程需要在节点之间传输数据，什么会限制数据传输的速度？"
  }
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            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

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                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
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                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
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                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
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                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  